Richard Bradley’s Medieval Skirmish rules are offered for free on the Tyneside Wargames Club site. There actually are quite a few free wargames rules there. All look quite playable and fun.
skirmish
Pike and Shotte Skirmish Rules
Richard Bradley of the Tyneside Wargames Club offers a set of free wargames rules for skirmishes in the English Civil War.
Warhammer Skirmish Rules
Here’s a set of rules for converting the large scale Warhammer Fantasy battles game to a skirmish version.
Breaking News Free Modern Skirmish Rules
Breaking News is a set of free wargames rules for modern skirmishes. From the introduction:
BN recreates the tension of today’s battlefields, scenes of difficult operations that are often called “peace keeping” missions, with the additional presence of civilians and the media.
In BN the main elements are the men and their choices on the field – these rules are not a “brochure” containing all the features of modern weapons.
BN is designed for “one-off” simulations. Build up your unit with group of miniatures and spend other points on EXTRAS (support fire, intelligence, rules of engagement…)
Twilight Small Scale Skirmish Rules
Hasslefree Miniatures has a trial set of their Twilight Small Scale Skirmish miniatures rules.